JP6826978B2 - Multi-layer structure and packaging materials with it - Google Patents

Description

The present disclosure relates to a multilayer structure and a packaging material including the same.

Foil laminates are widely used in food and medical packaging for sterilization, pasteurization, and retort applications. These packaging materials require good moisture resistance, product resistance, and chemical resistance at high temperatures. Adhesive laminates are preferred over extrusion laminates in certain applications because of their high chemical resistance on foil laminates. In contrast, extrusion lamination is primarily used in paper and low performance packaging materials such as chip bags. A method of preparing a high performance foil laminate without using an adhesive laminate is desirable in such applications.

The present disclosure relates to a multilayer structure and a packaging material including the same.

In one embodiment, the present disclosure provides a multilayer structure comprising a maleic anhydride-functionalized polyolefin layer coated on a metal-containing layer.

In another embodiment, the present disclosure provides a packaging material with a multi-layer structure.

It is a figure which illustrates one Embodiment of a multilayer structure.

The present disclosure provides a multilayer structure and a packaging material including the same.

The "maleic anhydride-functionalized (MAH-functionalized) polyolefin layer" includes (a) a layer containing a maleic anhydride-functionalized polyolefin resin, or (b) a maleic anhydride-functionalized polyolefin resin and one or more polyolefin resins. Means one of the layers containing the blend of.

"Maleic anhydride-functionalized polyolefin resin" means a polyolefin resin that is functionalized after a polymerization reactor with maleic anhydride.

"Metal-containing layer" means a metal leaf layer and / or a metallized polymer layer. The aluminum foil layer is the most commonly used metal foil layer. The metallized polymer layer is of a polymer film (eg, polyethylene terephthalate (PET), stretched polypropylene (OPP), unstretched polypropylene (CPP), polyethylene (PE), and polyamide, coated with a thin layer of metal, usually aluminum. Examples include, but are not limited to, polymer films containing one or more of them). Metallization is carried out using a physical vapor deposition process. The metal is heated and evaporated under vacuum. It condenses on a cold polymer film spread near a metal vapor source. Such metal coatings are much thinner than possible with metal leafs, in the range of 0.5 micrometers.

"Polymer" means a polymer compound prepared by a polymeric monomer, whether of the same type or different. Thus, the generic term polymer is used to refer to the term homopolymer (used to refer to a polymer prepared from only one type of monomer, with the understanding that trace impurities can be incorporated into the polymer structure), and below. Includes the term interpolymer as defined. Trace impurities (eg, catalyst residues) can be incorporated into and / or within the polymer.

"Polyolefin" means a polymer containing more than 50% by weight of one or more olefin monomers, such as ethylene or propylene-derived units (based on the weight of the polymer), optionally containing at least one comonomer. Good.

"Polyethylene" means a polymer having more than 50% by weight ethylene monomer derived units.

"Polypropylene" means a polymer having more than 50% by weight of propylene monomer derived units.

"Multilayer structure" means any structure having more than one layer. For example, a multilayer structure may have two, three, four, five, or more layers. A multi-layer structure can be described as having a layer specified by a letter. For example, a three-layer structure having a core layer B and two outer layers A and C may be designated as A / B / C.

In a first aspect, the present disclosure provides a multilayer structure comprising a maleic anhydride-functionalized polyolefin layer coated on a metal-containing layer. The present maleic anhydride-functionalized polyolefin layer contains a maleic anhydride-functionalized polyolefin. The present maleic anhydride-functionalized polyolefin may be maleic anhydride-functionalized polyethylene such as high-density polyethylene. You may also use maleic anhydride-functionalized polyethylene copolymers, terpolymers, and blends. Maleic anhydride functionality can be incorporated into the polymer by grafting or other reaction methods. In the case of grafting, the level of incorporation of maleic anhydride is typically less than 3 weight percent based on the weight of the polymer. Examples of commercially available maleic anhydride-functionalized polyethylene include those available under the trademark AMPLIFY available from The Dow Chemical Company (Midland, MI, USA), such as AMPLIFY TY1053H. Other examples of maleic anhydride-functionalized polyethylene include, among others, E.I. I. Available as the trademark FUSABOND, available from du Pont de Nemours and Company (Wilmington, DE, USA), among other maleic anhydride-functionalized polyethylene polymers, copolymers, and terpolymers, Chemtura Corporation (Middlebur , CT, USA), such as POLYBOND 3009 and POLYBOND 3029; among others, OREVAC available from the Arkema Group (Colobes, France), such as OREVAC 18510P; PLEXAR LyonDonderB. , For example, PLEXAR. TM. PX-2049; B. V. Grades available as trademark YPAREX available from DSM Engineering Plastics (Heerlen, the Netherlands), such as YPAREX 8305; and Trademarks available from ExxonMobil Chemical Company (Houston, TX, USA, eg, Polymer, EX). , EXXELOR PE 1040.

The maleic anhydride-functionalized polyolefin layer is applied to the metal-containing layer. Coating can be achieved by any acceptable mode such as extrusion lamination and / or extrusion coating.

Any metal-containing layer can form a substrate to which the polyolefin layer of maleic anhydride is applied. An exemplary metal foil includes an aluminum foil. If present, the foil may be corona treated or subjected to other treatments to improve adhesion, but is not required. An exemplary metallized polymer includes metallized polyethylene terephthalate. As is generally understood, the metal-containing layer can act as a barrier to oxygen or other gas permeation. In an alternative embodiment, the metal-containing layer may be replaced with a suitable non-metal-containing barrier layer.

The present disclosure further provides a multilayer structure according to any embodiment disclosed herein, except that the maleic anhydride-functionalized polyolefin layer comprises polyethylene functionalized after the reactor with maleic anhydride. Functionalization after the reactor means that the polyethylene is functionalized with maleic anhydride after the polyethylene has been formed in and exited the polymerization reactor. The grafting reaction can occur during the bulk reaction process or, optionally, in a coating process such as during extrusion coating.

The present disclosure further provides a multilayer structure according to any embodiment disclosed herein, except that the maleic anhydride-functionalized polyolefin layer comprises polyethylene, which has a density of 0.865 g / cc or greater. To do. All individual values and partial ranges from 0.865 g / cc and above are included and disclosed herein, for example, polyethylene densities of 0.865 g / cc and above, or optionally 0. It can be 885 g / cc or higher, or 0.90 g / cc or higher in the alternative, or 0.925 g / cc or higher in the alternative, or 0.935 g / cc or higher in the alternative. In certain embodiments, polyethylene has a density of 0.965 g / cc or less. All individual values and partial ranges from 0.965 g / cc or less are included and disclosed herein. For example, the density of polyethylene is 0.965 g / cc or less, or 0.960 g / cc or less in the alternative, or 0.955 g / cc or less in the alternative, or 0.950 g / cc or less in the alternative. There can be.

The present disclosure follows any embodiment disclosed herein, except that the maleic anhydride-functionalized polyolefin layer is formed from a blend of maleic anhydride-functionalized polyolefin and one or more non-functional polyolefins. Further provides a multi-layer structure.

The present disclosure further provides a multilayer structure according to any of the embodiments disclosed herein, except that one or more polyolefins are selected from the group consisting of polyethylene and polypropylene.

The disclosure further comprises a third polymer layer in which the multilayer structure is co-extruded with the maleic anhydride-functionalized polyolefin layer, resulting in a maleic anhydride-functionalized polyolefin layer of B and a metal-containing layer of A. Further provides a multilayer structure according to any embodiment disclosed herein, except that the third polymer layer will have an A / B / C structure of C. In certain embodiments, the third polymer layer may comprise a sealant resin.

The present disclosure further provides a multilayer structure according to any of the embodiments disclosed herein, except that the structure is a foil-type liquid board structure having any one of the following structures: (I) Low density polyethylene (LDPE) / printing board / LDPE / foil / MAH functionalized resin, (ii) LDPE / printing board / LDPE / foil / co-extruded MAH functionalized resin-sealant resin (here, sealant) The resin can be one or more selected from low density polyethylene, linear low density polyethylene, metallocene-catalyzed linear low density polyethylene (mLLDPE), and polypropylene), (iii) LDPE / printed paperboard / coextrusion. LDPE-ethylene acrylic acid (EAA) / foil / co-extruded MAH functionalized resin sealant resin (where the sealant resin is selected from low density polyethylene, linear low density polyethylene, mLLDPE, and polypropylene. (Can be one or more), and / or (iv) paper / LDPE / foil / co-extruded MAH functionalized resin-non-functional polyethylene.

The present disclosure comprises a multilayer structure according to any of the embodiments disclosed herein, except that the structure is a film / metallized film or film / foil structure having any one of the following structures: Further provided: (i) stretched polypropylene (OPP) -metal foil / co-extruded MAH functionalized resin-non-functional polyethylene, (ii) polyethylene terephthalate (PET) / PET-metal foil / co-extruded MAH functional Chemicald resin-non-functional polyethylene and / or (iii) PET / PE / metal foil / co-extruded MAH functionalized PE-non-functional polyethylene.

The present disclosure further provides a multilayer structure according to any of the embodiments disclosed herein, except that the structure is a retortable structure having any one of the following structures: (i). ) Polypropylene (PP) / printing paperboard / PP / metal foil / co-extruded MAH functionalized PE-PP, (ii) PET / co-extruded MAH functionalized PE-non-functionalized PE / metal foil / co-extruded MAH functionalized PE-PP, (iii) PET / co-extruded MAH functionalized PE-non-functionalized PE / metal foil / co-extruded MAH functionalized PE-PP / nylon film / PP, (iv) Extruded PET / MAH functionalized PE-non-functionalized PE / metal foil / co-extruded MAH functionalized PE-PP / EVOH / PP and / or (v) PET / PE / nylon film / co-extruded MAH functionalized PE-PE / metal foil / co-extruded MAH functionalized PE-PP / PP.

The present disclosure further provides a multilayer structure according to any of the embodiments disclosed herein, except that the maleic anhydride-functionalized polyolefin contains 0.01-2% by weight of maleic anhydride-derived units. All individual values and partial ranges of 0.01-2% by weight are included and disclosed herein, eg, maleic anhydride-derived units have lower limits of 0.01, 0.1, 1, 1 It can range from .2, 1.7, or 1.9% by weight to an upper limit of 0.05, 0.25, 1.1, 1.4, 1.8, or 2% by weight. For example, maleic anhydride-derived units in maleic anhydride-functionalized polyolefins are 0.01-2% by weight, or 0.01-1.1% by weight, or 1.1-2%. It can be in the range of% by weight, or optionally 0.5 to 1.7% by weight.

The present disclosure further provides a multilayer structure according to any embodiment disclosed herein, except that the metal-containing layer comprises a metallized polyethylene terephthalate layer.

The present disclosure further provides a multilayer structure according to any of the embodiments disclosed herein, except that the metal-containing layer comprises a metal leaf layer.

The present disclosure is any of the disclosures herein, except that the metal-containing layer is an aluminum foil having a thickness of 0.25 to 1.0 mil, more preferably 0.25 to 0.5 mil. Further provided is a multilayer structure according to the above embodiment. All individual values and partial ranges of 0.25 to 0.5 mils are included and disclosed herein, for example, the thickness of the aluminum layer is the lower limits 0.20, 0.25, 0. It can range from 3, 0.35, 0.4, or 0.45 mils to an upper limit of 0.3, 0.35, 0.4, 0.45, or 0.5 mils. For example, the thickness of the aluminum layer is 0.25 to 0.5 mils, or 0.25 to 0.60 mils, or 0.6 to 1.0 mils, or alternatives. Can be in the range of 0.25 to 0.50 mils. To those skilled in the art, the thickness of aluminum is defined as sufficient for the application.

FIG. 1 provides a chart that roughly illustrates the structure of the multilayer structure 1 of the invention. The multilayer structure 1 includes a metal-containing layer 10 (layer A) such as metallized polyethylene terephthalate (PET), and 40 represents a metal layer arranged on the PET. The multilayer structure further includes a polymer layer (layer B) containing maleic anhydride-functionalized polyolefin 20. In a particular embodiment, as illustrated in FIG. 1, the multilayer structure 1 of the invention further comprises a third polymer layer 30 (layer C) that can be co-extruded with layer B.

The disclosure further provides that the metal surface may be treated prior to use by any of a variety of methods, including corona treatment, flame treatment, or chemical treatment. This process is accomplished before applying the next layer to the aluminum.

The present disclosure is that the multi-layer structure exhibits a reduced adhesiveness of 50% or less as measured by a boil-in-bag test using any of the components described below in the description of the test method. Further provided are multilayer structures according to any of the embodiments disclosed herein. All individual values and partial ranges from less than 50% reduced adhesiveness are included and disclosed herein. For example, this decrease in adhesiveness may be 50% or less, or 40% or less in the alternative, or 30% or less in the alternative, or 20% or less in the alternative.

The present disclosure further provides packaging materials comprising the multilayer structure of any of the embodiments disclosed herein. In certain embodiments, the packaging material is a retort and / or sterile packaging material. The packaging material can be used in various embodiments to contain solids, slurries, liquids, or gases. By way of example, but not limited to, the packaging materials include acidic solutions, corn oil, alcohol, meat, cheese, sunscreen, shampoo, spices, soy sauce, coffee cream, flavored coffee, milk, beverages, detergents, sterile foods. May be used to contain hot-filled beverages, high-fat foods, baby wipes, iodine solutions, salad dressings, sauces, oven-enabled lids, cupstocks, sachets, and / or retort foods.

The following examples illustrate the invention, but are not intended to limit the scope of the invention. Inventive Example 2 is a reference example.

All of the examples of the present specification are made by using a metal foil layer (metal-containing layer) backed with PET, and this metal foil layer is made of 1 mil PET using an adhesive for laminating urethane. It was prepared by adhering the film to one side of a 0.35 mil aluminum foil. All of the examples herein utilize a Black Clawson extruded coating co-extrudable lab line equipped with a 0.9 meter wide die on the foil surface of a metal leaf layer with a PET backed polymer layer. Extruded or co-extruded to coat. Samples were taped to one side and dropped onto a moving substrate, 80 g / m ² brown (unbleached) kraft paper moving lines at 90 m / min. The sample was coated with a coextruded 300 ° C. molten polymer.

Three comparative multilayer structures (Comparative Examples 1-3) were made using a non-maleic anhydride functionalized polymer layer as shown in Table 1. Example 1 of the invention was produced using a layer in which a maleic anhydride-functionalized polyethylene / non-functionalized polyethylene blend was co-extruded with the non-functionalized polyethylene as shown in Table 1. In each case, layer A is aluminum coated PET and the remaining layers are described in Table 1. Table 1 further shows the adhesiveness of the polymer layer to the metal-containing layer before and after the boil-in-bag test. As can be seen in Table 1, only Example 1 of the invention maintained good adhesion after the "1: 1: 1" boil test.

DOWLEX 3010 is a polyethylene having a density of I ₂ and 9.21 g / cc at 5.4 g / 10 min, which is commercially available from The Dow Chemical Company (Midland, MI, USA). PRIMACOR 3440 is an ethylene / acrylic acid copolymer having a density of 10 g / 10 min _{I 2} and 0.938 g / cc, which is commercially available from The Dow Chemical Company. AMPLIFY IO 3701 is a zinc ionomer of ethylene / acrylic acid copolymer having 5.2 g / 10 min I ₂ and is commercially available from The Dow Chemical Company.

Two additional comparative multilayer examples (Comparative Examples 4-5) having the structures shown in Table 2 were produced. Examples 2-6 of the invention were produced using maleic anhydride-functionalized polyethylene with different levels of maleic anhydride. Table 2 further provides adhesion before and after the boil-in-bag test.

LDPE 722 is a non-functional polyethylene having a density of I _{2 at} 8 g / 10 and 0.920 g / cc and is commercially available from The Dow Chemical Company. The maleic anhydride functionalized polyethylene resin in Example 2-6 of the present invention has a density of I _{2 of} 6.0 g / 10 and 0.925 g / cc. As can be seen in Table 2, only the embodiments of the invention show good adhesion after the boil-in-bag test, even with a very low amount of maleic anhydride graft.

Without being bound by theory, the relative chemical resistance of layer B, which is a maleic anhydride graft polymer, can act as a chemical boundary for the reducing effect of the inclusions in the test structure. Surprisingly, there was an increase in adhesive strength after the boil-in-bag test on the embodiments of the invention where the level of the maleic anhydride graft polymer in the metal contact layer was greater than 1% by weight.

Those skilled in the art will recognize that the layers described in Tables 1 and 2 are a small group of multilayer structures in which additional layers in the entire structure, such as printing layers, sealing layers, paper, etc., may be present.

Test method The test method includes the following.
Polymer density is measured according to ASTM D792.
I ₂ is measured according to ASTM D1238 (190 ° C./2.16 kg).
The boil-in-bag test is performed according to the following steps.
Step 1. Cut out a rectangular laminate of suitable size to make a completed pouch with an internal size of about 10 cm x 15 cm.
Step 2. Heat fuse the bottom and sides of the rectangular piece at 200 ° C. and 50 psi.
Step 3: The sachet is filled with a mixture of 100 grams of Meijer distilled white vinegar / Mazola corn oil / Heinz tomato ketchup (weight ratio 1: 1: 1). Seal the top of the pouch after filling.
Step 4: Place the pouch in boiling water and leave it for 1 hour.
Step 5: Remove the pouch from the water. Cut the pouch and open it to empty the contents. Cut a 1-inch strip and measure the stacking adhesion strength on a tensile tester. This step is completed within 10 minutes after step 4.

Adhesion between the foil layer (Layer A) and the MAH functionalized PE layer (Layer B) (before and after the boil-in-bag test) was performed using the Twing-Albert Tensile Tester at a test rate of 10 inches / min. Measured according to ASTM D1876.

Fourier Transform Infrared Spectroscopy (FTIR) Analysis-Maleic anhydride content.
The concentration of maleic anhydride, determined by the percentage to polymer reference peak of the peak height of maleic anhydride at a wavenumber 1791cm ^-1, in the case of polyethylene carried out in the wavenumber 2019cm ^-1. The maleic anhydride content was calculated by multiplying this ratio by an appropriate calibration constant. The equation used for the maleic acid graft polyolefin (using the reference peak for polyethylene) has the following form, as shown in Equation 1A.

The calibration constant A can be determined using the C13 NMR standard. Actual calibration constants may vary slightly depending on the instrument and polymer. The signal at wavenumber 1712 cm- ¹ corresponds to the presence of maleic acid, which is negligible for newly grafted material. However, gradually, maleic anhydride is easily converted to maleic acid in the presence of moisture. Depending on the surface area, significant hydrolysis can occur in just a few days under ambient conditions. This acid has a prominent peak at a wave number of 1712 cm- ¹ . The constant B in Equation 1A is a correction for the difference in extinction coefficient between the anhydride group and the acid group.

The sample preparation procedure is typically initiated by making a press product with a thickness of 0.05-0.15 mm in a heated press machine at 150-180 ° C. for 1 hour between two protective films. To do. MYLAR and TEFLON® are suitable protective films for protecting the sample from the platen. Do not use aluminum foil (maleic anhydride reacts with aluminum). The platen should be pressurized for about 5 minutes (about .10 tons). Samples were cooled to room temperature, placed in a suitable sample holder and then scanned in FTIR. A background scan should be performed before each sample scan or as needed. The accuracy of the test is good and the inherent variability is less than ± 5%. Samples should be stored with a desiccant to prevent excessive hydrolysis. Maleic anhydride and acid are represented by peaks at about 1791 and 1712 cm- ¹ , respectively.

Since the present invention may be embodied in other forms without departing from its spirit and essential attributes, the appended claims are used to indicate the scope of the invention, rather than the specification described above. Should be referred to. It should be added that the present invention includes the following aspects.
[Aspect 1]
A multi-layer structure comprising a polymer layer containing a maleic anhydride-functionalized polyolefin applied to a metal-containing layer.
[Aspect 2]
The multilayer structure according to aspect 1, wherein the maleic anhydride-functionalized polyolefin is extruded and laminated and / or extruded and coated on the metal-containing layer.
[Aspect 3]
The multilayer structure according to aspect 1, wherein the polymer layer is formed of polyethylene functionalized after a reactor with maleic anhydride.
[Aspect 4]
The multilayer structure according to aspect 3, wherein the polyethylene-based polymer is a high-density polyethylene having a density of 0.865 g / cc or more.
[Aspect 5]
The multilayer structure according to aspect 3, wherein the polyethylene-based polymer is a high-density polyethylene having a density of 0.90 g / cc or more.
[Aspect 6]
The multilayer structure according to aspect 3, wherein the polyethylene-based polymer is a high-density polyethylene having a density of 0.935 g / cc or more.
[Aspect 7]
The multilayer structure according to aspect 3, wherein the polyethylene-based polymer is a high-density polyethylene having a density of 0.950 g / cc or more.
[Aspect 8]
The multilayer structure according to aspect 1, wherein the maleic anhydride-functionalized polyolefin layer is formed from a blend of maleic anhydride-functionalized polyolefin and one or more polyolefins.
[Aspect 9]
The embodiment in which the maleic anhydride-functionalized polyolefin layer is formed from a blend of a maleic anhydride-functionalized polyolefin and one or more polyolefins, and the maleic anhydride blend component is more than 1% by weight in the layer. 8. The multilayer structure according to 8.
[Aspect 10]
The multilayer structure according to aspect 8, wherein the one or more polyolefins are selected from the group consisting of polyethylene and polypropylene.
[Aspect 11]
A third layer co-extruded with the maleic anhydride-functionalized polyolefin layer is further provided, and as a result, the multilayer structure has the polymer layer B and the metal-containing layer A, and the third layer. The multilayer structure according to aspect 1, wherein the layer is C and has an A / B / C structure.
[Aspect 12]
The multilayer structure according to aspect 1, wherein the maleic anhydride-functionalized polyolefin contains 0.01 to 2% by weight of maleic anhydride-derived units.
[Aspect 13]
The multilayer structure according to aspect 1, wherein the metal-containing layer includes a metallized polyethylene terephthalate layer.
[Aspect 14]
The multilayer structure according to aspect 1, wherein the metal-containing layer includes a metal foil layer.
[Aspect 15]
The multilayer structure according to aspect 14, wherein the metal-containing layer has a thickness of 0.25 to 1.0 mil.
[Aspect 16]
The packaging material having the multilayer structure according to the first aspect.
[Aspect 17]
The packaging material according to aspect 16, wherein the packaging material is a retort and / or sterile packaging material.

Claims (3)

A polymer layer containing maleic anhydride-functionalized polyethylene applied to a metal-containing layer, wherein the maleic anhydride-functionalized polyethylene contains 0.068 to 0.27% by weight of maleic anhydride-derived units. It has a multi-layered structure with
The polymer layer was formed from polyethylene functionalized after the reactor with maleic anhydride.
The polyethylene is a high-density polyethylene having a density of 0.950 g / cc or more.
The multilayer structure further comprises a third layer co-extruded with the polymer layer containing the maleic anhydride-functionalized polyethylene so as to have an A / B / C structure, where B is the polymer layer. Yes, A is the metal-containing layer, C is the third layer, and
The multilayer structure in which the metal-containing layer includes a metallized polyethylene terephthalate layer . Wherein said polymeric layer comprising a maleic anhydride functionalized polyethylene, the maleic anhydride-functionalized polyethylene is formed from a blend of one or more polyolefins, a multilayer structure of claim 1. The polymer layer containing the maleic acid-functionalized polyethylene, the maleic anhydride-functionalized polyethylene is formed from a blend of one or more polyolefins, component of the blend, 1 wt.% In the polymer layer The multilayer structure according to claim 1 .